GB2209672A

GB2209672A - Incontinence pad

Info

Publication number: GB2209672A
Application number: GB8721598A
Authority: GB
Inventors: Richard D B Robinson
Original assignee: Robinson and Sons Ltd
Current assignee: Robinson and Sons Ltd
Priority date: 1987-09-14
Filing date: 1987-09-14
Publication date: 1989-05-24
Anticipated expiration: 2007-09-14
Also published as: GB2209672B; GB8721598D0

Abstract

An incontinence pad comprises an absorbent core (1) of e.g. fluffed wood pulp within a tissue cover. In contact with each longitudinal side edge (2) of the core is a tow (3) of hydroneutral fibres extending along substantially the entire length of the core. The tows (3) may conveniently be surface bonded tows of polypropylene/polyethylene bicomponent fibres. A liquid impervious layer (4) covers the underside of the pad and extends up the side of the tows (3). During slow rate urine discharge the urine is absorbed directly by the core (1). If a high rate of urine discharge occurs the tows (3) conduct non-absorbed urine away from the point of application to be absorbed along the full length of the core. <IMAGE>

Description

INCONTINENCE PAD The present invention relates to an incontinence pad. More particularly, but not exclusively it relates to an incontinence pad intended to promote distribution of urine along the pad, and thereby render the pad able to deal adequately with high urine flow rates. Another aspect of the invention relates to a method of making a component of such a pad.

Incontinence pads are well known and used.

They usually have a central core of absorbent material, for example cotton wool, wood pulp or cellulose, within a liquid-permeable coverstock. A liquid-proof layer may be provided on the side of the core remote from the user.

One problem with pads of this type is that since urine is applied to the pad over only a small area the rate at which the urine is absorbed is limited by the rate at which the pad will transmit the urine away from the point of application. At low application rates, this presents no problems, but at high application rates such as are encountered if urine is rapidly discharged, the core cannot transmit the urine away from the area of application quickly enough, with the result that the core becomes saturated near the point of application, and urine leaks from the pad.

Attempts have been made to overcome this problem, or at least reduce the resulting problem of leakage, by providing means for improving the distribution of urine along the pad. For example U.K.

Patent No. 2138303 suggests that three strips of watertransmitting material are disposed on the upper surface (that nearest the user) of the absorbent core to provide a passage along which unabsorbed urine can flow to an unsaturated part of the core. The material used to transmit urine is a polyester open cell foam.

However, for the economical manufacture of incontinence pads it is necessary for the pads to be manufactured by automatic machinery in which the pads are produced as a continuous end-to-end stream. This in turn requires that the materials from which the pads are made are available in continuous lengths of at least several hundred metres. Open cell polyester foams are not available commercially in such lengths. Furthermore the proposal of GB 2138303B to place the foam on the upper surface of the core has been found to reduce the comfort of the pad especially when the foam material used is an open-celled skeletal polyurethane polyester foam.

It is an object of the present invention to provide an improved water transmitting material and to provide an improved incontinence pad incorporating it.

According to a first aspect of the present invention, there is provided an incontinence pad comprising a central core of absorbent material having an upper surface adapted in use to be presented towards the user, a lower surface opposite thereto and two elongate side surfaces, two liquid conducting means disposed along and in contact with said elongate side surfaces, each liquid conducting means comprising a tow of synthetic fibres adapted to allow free flow of liquid therealong from a saturated zone of said core to an unsaturated zone, and a liquid-pervious cover surrounding said core and liquid conducting means.

A liquid-impervious layer may be provided within or without the cover over the lower surface of the core and up the sides.

The synthetic fibres may be of any suitable material for example polyethylene, polypropylene, polyamide, polyester, polyvinyl acetate, polyurethane, using either homo-polymers or co-polymers of the above and other thermoplastic components. Preferably, the fibres are bicomponent fibres with a sheath of lower melting point fibres of polyethylene and a core fibre of polypropylene. The bicomponent fibres may be of the "skin/core' or "side by side" configuration. A preferred fibre is that supplied by Jacob Holm - Danaklon ES.HB. 6.7 decitex - 40mm staple. Preferably, the fibres have a hydroneutral finish [as hereinafter defined].

The outer surface of the tow may be lightly bonded, optionally by rapid heat treatment.

According to a second aspect of the present invention there is provided a method of making a liquid conducting means comprising the steps of providing a sliver of synthetic fibres, and passing said sliver through a heated tube substantially in contact with the inner wall thereof, the temperature and speed of passage being selected to cause at least some of the surface fibres of the sliver to soften and bond together, whereby the outer surface of the thus formed tow comprises a liquid-pervious skin.

Preferably the synthetic fibres are bicomponent fibres, preferably having one side of lower melting point polyethylene and one side of polypropylene of higher melting point.

It has been found that in making the sliver from fine fibres of the type conventionally used in the production of non-woven fabrics, the bond of the sliver tends to collapse under pressure from the wear's legs.

Accordingly, the fibres should be somewhat coarser than those conventionally used in the production of non-woven fabrics, but fine enough to be readily formed into the desired tow and to be comfortable in use.

We have found that optimum results are obtained if fibres used are neither hydrophobic nor hydrophilic.

Two tests have been used to define the degree of hydrophilicity etc. Firstly, the sinking time of the opened fibre from a bale is tested by the British Pharmacopoeia (BP) 1980, (Surgical Dressings Section) Test Method SDMX1. A. Test 1. In this test a copper wire basket 80mm high by 50mm diameter, containing a weighed amount of fibre (approximately 1gum) is dropped in the horizontal position 1Omm above the surface of a beaker of water at 200C. The time for the basket to disappear below the surface is measured. This is described as the sinking time. The sinking time for the fibres used in the present invention should preferably be between 5 seconds and 15 seconds and should more preferably be approximately 10 seconds.A fibre which would conventionally be regarded as hydrophilic would have a sinking time of less than 2 seconds whilst a fibre conventionally regarded as hydrophobic would have a sinking time of more than 60 seconds. The second test used to identify fibres suitable for use in the present invention is a "Wicking Test" on the made-up bonded tow.

This test has been devised by Dr. Alan Cottenden of the Department of Urodynamics, St. Pancras Hospital, London.

In this test, the bonded tow (approximately 17mm in diameter) is immersed in the test fluid (synthetic urine, or 0.9% saline solution).

The time for the fluid to "wet out" the tow below the water level is measured, together with the height above the water level to which the fluid wicks after 60 seconds. The preferred fibres of the present invention provide a tow having a wetting out time (40mm to O) of 20-5 seconds and a wicking height after 60 seconds of 0-5mm with preferred values of 15 seconds and Omm respectively. In contrast a hydrophilic fibre has a wetting out time of less than 5 seconds and a wicking height of 7-38mm and a hydrophobic fibre has a wetting out time of greater than 40 seconds and a wicking height of Omm or less than Omm.

Fibres producing a sinking time of between 5 and 15 seconds in the first test or a wetting out time of between 20 and 5 seconds in combination with a wicking height of 0-5mm in the second test are referred to herein as "hydroneutral fibres".

User trials have shown that when the bonded tow was hydrophilic, the absorbent capacity of the pad was increased, and the pads were more likely to feel wet and uncomfortable on the wearer's legs. The pads with hydrophobic tow tended to have a lower absorbent capacity and to produce more pads that leaked than those with the hydroneutral tow. This confirms the expectation that the tow is not as efficient in transmitting urine as the hydroneutral tow.

The tube may be rotated during passage of the sliver. The exit end of the tube may be provided with a die which is preferably treated in a manner to prevent sticking of the fibres e.g. by coating with PTFE. The die preferably has an inside diameter of 12-25mm with a preferred range of 15-20mm.

Preferably the sliver is formed by carding bicomponent high bulk polypropylene fibres (e.g. Danaklon ES.HB) for example of 40mm staple and 6.7 dTex, into a sliver of density in the region of 10-12 g/m.

The linear speed of passage of the sliver is preferably at least 5-lOm/min; and the temperature of the tube wall is preferably in the range 130-1450C with preferred values above 1400C. In general, the higher the process speed the higher will be the required die temperature, and it is believed that processing speeds of up to 60m/min may be possible at die temperatures of up to 1700C.

Though it is desirable to add "false twist" to the unbonded tow, to aid processing, it is possible to bond the sliver without imparting twists to the sliver.

The rotation of the tube may be 10 to 20 r.p.m. at 5m/min to impart 7 to 10 twists per meter to the finished tow.

Proportionately, higher rotary speeds are required for higher linear processing speeds.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-sectional view of an incontinence pad embodying the invention; and Figure 2 is a schematic view of an apparatus to prepare the tow.

Referring now to Figure 1, which is a crosssection across an incontinence pad, an absorbent core 1 of fluffed wood pulp within a tissue cover has an elongate block shape. In contact with each of the two longitudinal side edges 2 of the core is a tow 3 of polypropylene fibres having its surface bonded. The tows 3 extend substantially along the entire length of the core and act to convey liquid from a saturated zone of the core 1 to an unsaturated zone.

The pad is intended to be presented to the user with its upper (as seen in Figure 1) surface towards the user.

An impervious sheet of polyethylene 4 covers the lower surface of the core and is attached at each edge by adhesive 5 to an outer edge of each tow.

The assembly of core 1, tows 3, and impervious lower sheet 4 is wrapped in a liquid-pervious coverstock 6 of polypropylene.

A paper covered adhesive strip 7 is provided to allow the pad to be secured in position to a garment of the user.

As can be seen, the location of the tows 3 permits the entire upper surface of the core to be available to absorb a low rate of urine flow, but in cases of higher urine flow which the core itself cannot absorb locally, the tows act almost in the manner of gutters, carrying excess liquid from a saturated area to an unsaturated area of the core.

The tows 3 are prepared as described below from hydrophilic or preferably hydroneutral fibres. Fibres of staple 40mm and dTexd 6.7 are carded into a sliver 10 of density approximately 10-12 g/m.

The sliver 10 is passed at a linear speed of approximately 5-1 0m/min to a heated rotating tube 11.

The tube is rotated at a speed of approximately 10-20 revolutions per minute by means of motor 12 and belt drive 13, and heated to a temperature in the region of 1400C.

The purpose of this heating step is to produce a liquid-pervious skin on the outside of the tow by heat softening of at least some of the external lower melting point elements of the bicomponent fibres and bonding such softened fibres.

The exit point of the tube 11 comprises a die 14 having an aperture of diameter between 15 and 20mm inside diameter preferably approximately 17mm inside diameter.

The rotation of the tube causes a false twist in the produced tow, approximately 7 to 10 twists per metre.

Obviously, if the linear speed is increased in order to increase throughput, as is desirable, the temperature of the tube must be increased accordingly to produce the same surface bonding effect.

The rotational speed of the tube may also be varied and this speed, together with the linear speed of the sliver 10, will determined the applied twist of the tow.

Claims

1. An incontinence pad comprising a central core of absorbent material having an upper surface adapted in use to be presented towards the user, a lower surface opposite thereto and two elongate side surfaces, two liquid conducting means disposed along and in contact with said elongate side surfaces, each liquid conducting means comprising a tow of synthetic fibres adapted to allow free flow of liquid therealong from a saturated zone of said core to an unsaturated zone, and a liquid-pervious cover surrounding said core and liquid conducting means.

2. An incontinence pad according to claim 1 wherein the synthetic fibres of said tow are bicomponent fibres.

3. An incontinence pad according to claim 1 or claim 2 wherein said fibres are hydroneutral (as hereinbefore defined).

4. An incontinence pad according to any preceding claim wherein the outer surface of each said tow of synthetic fibres is lightly bonded.

5. An incontinence pad according to claim 4 wherein said bonding is effected by rapid heat treatment of the tow.

6. An incontinence pad according to any preceding claim wherein the pad includes an impervious layer which covers the said lower surface of the central core, and extends laterally beyond the edges of the core to cover the adjacent surface of the tows.

7. An incontinence pad according to claim 6 wherein the impervious layer covers the outwardly directed lateral services of the tows.

8. An incontinence pad according to claim 7 wherein said impervious layer is adhesively secured to the tows.

9. An incontinence pad substantially as hereinbefore described with reference to the accompanying drawing.

10. A method of making a liquid conducting means comprising the steps of providing a sliver of synthetic fibres, and passing said sliver through a heated tube substantially in contact with the inner wall thereof, the temperature and speed of passage being selected to cause at least some of the surface fibres of the sliver to soften and bond together, whereby the outer surface of the thus formed tow comprises a liquid-pervious skin.

11. A method according to claim 10 wherein said synthetic fibres are bicomponent fibres.

12. A method according to claim 11 wherein said bicomponent fibres include a polyethylene component and a polypropylene component.

13. A method according to any of claims 10-12 wherein said fibres have a hydroneutral (as hereinbefore defined).

14. A method according to any of claims 10-13 wherein said heated tube is rotated as said sliver is passed therethrough.

15. A method according to any of claims 10-14 wherein the downstream end of said tube is in the form of a tapered die.

16. A method of making a liquid conducting means, substantially as hereinbefore described with reference to the accompanying drawing.

17. A liquid conducting means formed by the method of any of claim 10-16.

18. An incontinence pad according to any of claims 19 wherein each tow is a liquid conducting means according to claim 17.